Egbert w



E. W. SPERRY.

HARDENING 1115s.

Patented Feb. 2,1869.

tluit EGBERT W. SPERRY, OF .WOLCCTTVIL'LE, CONNECTICUT.-

Lam Patent No. 86,467, dated February 2, 1869.

IMPROVEMENT IN HARDENIH'G- DIES.

{Elie Schedule referred to in these Letters Patent and making part ofthe same.

To all wham t't ma/y concern Be it known that I, EGBERT W. SPERRY, ,of'W'olcottville, county of Litchfield, and State of Connecticnt, haveinvented certain new and useful Improvements in Hardening Dies; and to'enableothers skilled in the art to make and use the same, I willproceed to describe its construction and operation, by referring to thedrawings, in which the same lettersindicate like partsin each ofthefigures.

The nature of this invention consists in the mode or process ofhardening dies, as follows:

A fire-proof box is 'first prepared, a little longer and wider than thelength and width of the die, and about the same in depth as the depth ofthe die... Into the bottom of this box is placed a layer of pulverizedcharcoal. Then the face of the die is placed upon the surliwe of thecharcoal-dust, (after smearing the die-face with a preparation of ivoryor bone-black;) then fi1ling-up the side and end space with charcoal,closely packed, to a point near the top edge of the box; then fillingthe remaining space, from the edge of the box to the edge of the die,with fire cla-y.

. After this has been done, the box is laid on the grate of a. furnace,and a fire kindled over and around it, and heated to a temperature toproduce a white heat on the upper surface of the die, (the bottomproper, of the die,) after which the box with the die is removed andallowed to stand until. the exposed surface has so far cooled as toprevent it from hardening by immersion in hardening-fluids. Then the dieis quickly lifted from the box and immersed in the hardening-fluid, theresult of which is, the thee of the die will be hardened, so as toresist the action of afile, while the base, or bottom proper of the die,will remain susceptible to the action 'of'a file.-

In the accompanying drawings- Figure l is abox, with the die placedtherein upside or face down.

Figure 2 is a section cutlengthwise through the centre of the box,showing the box, charcoal, die, and fire-clay.

c isthe box, which is made larger in width and breadth than the die, forthe purpose of providing packing room for charcoal. The depth of the boxis about the same depth of the die, so that when the die isplaced uponthe packing, the upper side will be above the side of the box.

. 'b is the charcoal-packing, which surrounds the me, (under side,sides, and ends,) nearly to the upper edge thereof 0 is the die.

d is the fire-clay, which closes the-space over the charcoal between theedge of the box and the edge of the die.. 1

Thus Iain enabled tocarbonize the face of the die, and decarbonizeihebase or bottom of the die, and prevent'any scale from forming on theface, and harden the face without hardening the base, thus doing awaywith the ordinary process of first hardening and then tempering the die,whereby so many dies are cracked and utterly destroyed.

I believe I have thus shown the nature, operation, and advantage of thisinvention, so as to enable others skilled in the artto make and use thesame therefrom.

. What I claim, therefore, and desire to secure by Letteis Patent, 'is VThe process of hardening dies, substantiallyas shown and described.

E. W. SPERRY. [L. s.] Witnesses:

E. W. Buss, JEREMY W. Buss.

